9,000 Larvae Later…

Jaclyn Caruso, Salem State University

Me UrchinFindings: In my previous post, I talked about how counting larval stages and measuring their skeletons could help us determine the lethal and sublethal effects of preservatives used in cosmetics and other personal care products on development. What we found was pretty surprising.

After two days of development in normal conditions, sea urchin larvae should be in the pluteus stage and have 2 or 4 arms. The arms are important because they are surrounded by bands of cilia that help the larva swim and feed. In the controls and at the lowest concentrations that we tested (0.1, 1, and 10 parts per million), the majority of the larvae successfully reached this stage. However, things got interesting at about 32 ppm.

We found that at concentrations at and above 32 ppm, the larvae generally grew shorter arms, had a smaller body size, and were more asymmetric. Any of these abnormalities could potentially have fatal consequences for the larvae. We also found that at high enough concentrations of the preservatives, development will fail completely. At concentrations of 1000 ppm, almost 100% of the fertilized eggs that we added to the jars didn’t develop past the early cleavage stages. This means that development was stopped almost instantly.

If you remember back to my first post, we wanted to test how parabens compared to the newer alternatives they were replaced with. Of the three preservatives we tested, the paraben caused changes in growth and failure of development at the lowest concentrations. The other two preservatives fared slightly better, suggesting that the personal care products industry may have made a good decision by switching. However, because we saw harmful effects in all three preservatives, we can’t say that they are completely safe for marine life at these concentrations.

This summer has taught me a ton about scientific research. I always expected it to require a lot of time, patience, and dedication, and my expectations were absolutely confirmed. In total, we counted and categorized 8,919 larvae and measured 2,224. That’s a lot of long hours at the microscope, and a lot of data to analyze. But, our results were definitely worth it, and I’m greatly looking forward to my next research experience!

Larval Stages

Left: normal preserved plutei in the 4- or 2-arm stage. Right: abnormal preserved individuals with incorrectly shaped skeletons or at early stages of development. Jaclyn Caruso, 2018


Thank you to Dr. Bob Podolsky (CofC) for his mentorship, Dr. Cheryl Woodley (NOAA) for providing her procedures and resources, and Pete Meier (CofC) for teaching me the ropes of setting up aquaria. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.